1. Technical Field
The present invention relates to a pregelatinized or cold water dispersible, modified starch and the process for its preparation. More specifically, the present invention is directed towards a modified sago-based starch having improved gelling properties wherein the starch gels ‘instantaneously’ or fast relative to other gelling starches.
2. Background Information
Food systems such as pie fillings, puddings and jellies have a set or gel texture when prepared. These types of food systems typically contain gelling agents and must be cooked to effect gelation. Common gelling agents used for this purpose include agar, gelatin, cornstarch, pectin, carrageenin, algin, and combinations of locust bean gum and xanthan gum. It is known that starch can be used to add texture to products by means of its gelling properties. For example, acid converted starch derivatives that are converted to a certain water fluidity level will retrograde to a gel when cooked. These include, for example, derivatives of corn, potato, tapioca and wheat.
Conventional starch-based puddings are exemplary of food products that require cooking to effect gelation. These puddings generally include an ungelatinized starch, flavorings, sweetening agents, etc., and are prepared for consumption by adding milk, cooking until the starch is gelatinized, pouring the cooked mixture into a bowl or individual serving dish, and cooling and/or refrigerating.
However, these types of food systems are disadvantageous not only because of the cooking required to impart the gel texture thereto, but also due to other requirements of the food system. For example, gelatin can be used only after dissolution in very hot water, and typical pectins used in jellies require about 65% sugar solids to produce a gel.
There are other known food systems having a set or gel texture that form a gel without cooking. Many of these products are dairy based and include pregelatinized (i.e., cold water dispersible) starch and one or more setting agents that are usually phosphate salts (e.g., tetrasodium pyrophosphate), as well as flavoring, sweetening and coloring agents. The set or gel properties of these food systems are due to the interaction between the phosphate salts and the casein and calcium ion provided by the milk, and not with the starch ingredients in the formulation. Here, the pregelatinized starch functions as a viscosity builder or thickening agent. However, it is not the prime factor in the development of the gel structure of the prepared food system.
These uncooked, so-called ‘instant’ food formulations typically do not have the firm gel structure of the cooked formulations. For instance, they do not cut as cleanly with a spoon. Further, their texture, rather than being smooth, can be characterized as ‘grainy’ in both appearance and ‘mouth-feel’. Also, the setting salt agents are not operative at low pH or in non-dairy based food systems.
Non-dairy based food systems having a set or gel texture that form a gel without cooking are also known. U.S. Pat. No. 4,207,355 teaches a cold-water dispersible, modified tapioca starch that forms a gel when dispersed in cold water. The starch product is obtained by drum drying a tapioca starch that has been converted to specified water fluidity and reacted with a crosslinking agent to give Brabender viscosity parameters within a selected range. The patent teaches that simply crosslinking the starch and drum drying it without converting it to fluidity starch does not result in a product having gelling properties.
The reverse process of U.S. Pat. No. 4,207,355, i.e., crosslinking native tapioca starch, then converting the starch to its fluidity form, and lastly drum drying it, is disclosed in U.S. Pat. No. 4,229,489.
U.S. Pat. No. 4,228,199 teaches a cold-water dispersible, modified potato starch that forms a gel when dispersed in cold water. The starch product is obtained by drum drying a potato starch that has been reacted with a crosslinking agent to give Brabender viscosity parameters within a selected range. The step of converting the starch to specified water fluidity required in U.S. Pat. Nos. 4,207,355 and 4,229,489 is not required in the '199 patent. However, if desired, the potato starch can be converted to specified water fluidity either before or after the crosslinking step.
U.S. Pat. No. 4,391,836 discloses instant gelling native tapioca or native potato starches that are made cold water dispersible by drum drying the native starch, and then heat treating the drum dried starch to reduce its viscosity to within specified limits. Lightly converted tapioca or potato starches can be used in place of the native starches.
Typically, gum confections use a fluidity starch or a combination of a high amylose starch and a fluidity starch which are cooked at a moisture content above the final moisture content of the confectionery, and deposited as a thin, hot liquid into a mold generally formed of dry starch. The starch in the mold forms the confectionery pieces and serves to reduce the moisture content of the confectionery to the level of the end product. This starch mold casting process has the disadvantage of long processing time in order to obtain gel strength integrity sufficient for handling and packaging as well as a desirable product texture.
U.S. Pat. No. 6,447,615 teaches converted sago fluidity (i.e., viscous) starches having a water fluidity of from about 40 to about 80. The sago fluidity starches form exceptionally strong gels and have a faster gelling rate than fluidity starches derived from other plants. However, the sago fluidity starch gels tend to have weaker gel strength at lower solids and are subject to syneresis. While such a starch can be useful in confectioneries, it is undesirable in food formulations such as pie and cream fillings, puddings, spreads and imitation jellies.
Accordingly, there is a need for an instant gelling starch that forms strong gels more rapidly than presently available instant gelling starches. Further, there is a need for an instant gelling starch that has a smooth texture and lack of graininess often found in cold water dispersible starches.